Torsionally Stabilized Endoprosthetic Device

Abstract

An improved endoprosthetic device includes a modular rotational component affixed along the stem of a humeral prosthesis or a femoral prosthesis. The rotational component axis of rotation is coaxial with the stem, and its axis of rotation is located in close proximity to the intramedullary stem of the prosthesis or in close proximity to the distal articulation of the prosthesis. The rotational component includes a lobe ring adapted to limit the axis of rotation of the component. The lobe ring further includes ramp features that gradually limit the rotation of the rotational component shaft, thereby reducing the felt impulse when rotated to a stop, or no ramp feature to allow maximum rotation as allowed by the patient's soft tissue.

I claim: 
     
         1 . A torsionally stabilized humeral or femoral prosthesis, the humeral or femoral prosthesis comprising:
 a first rotational component and a shaft component affixed intermediate to a proximal articulation and a related distal articulation, with the first rotational component axis of rotation substantially coaxial with the shaft component, the first rotational component allowing rotation of the distal articulation relative to the proximal articulation.   
     
     
         2 . The prosthesis of  claim 1 , the first rotational component comprising a Morse taper for affixation with one or more additional prosthesis segments to establish a desired length of the shaft component. 
     
     
         3 . The prosthesis of  claim 1 , the first rotational component comprising a porous mesh metal surface treatment for soft tissue attachment thereto. 
     
     
         4 . The prosthesis of  claim 1 , the first rotational component comprising a lobe ring for limiting the degree of the relative joint rotation. 
     
     
         5 . The prosthesis of  claim 1 , the first rotational component comprising a lobe ring for limiting the degree of rotation, the lobe ring comprising a ramp feature for gradually arresting the relative joint rotation. 
     
     
         6 . The prosthesis of  claim 1 , the first rotational component comprising a humeroulnar articulation. 
     
     
         7 . The prosthesis of  claim 1 , the first rotational component comprising a humeroulnar articulation, the humeroulnar articulation further comprising a second rotational component. 
     
     
         8 . The prosthesis of  claim 1 , wherein the first rotational component is modular comprising at least one Morse taper for affixing at least one additional prosthesis segments. 
     
     
         9 . A method for reducing the torsional stresses on a humeral prosthesis, the method steps comprising:
 affixing a first rotational component at a location along a humeral shaft intermediate to the humeral proximal articulation and the humeral distal articulation.   
     
     
         10 . The method of  claim 9 , the method steps further comprising:
 locating the first rotational component nearer to an intramedullary stem of the humeral prosthesis.   
     
     
         11 . The method of  claim 9 , the method steps further comprising:
 locating the first rotational component nearer to the distal articulation of the humeral prosthesis.   
     
     
         12 . A method for reducing the torsional stresses on a femoral prosthesis, the method steps comprising:
 affixing a first rotational component at a location along a femoral shaft intermediate to the femoral proximal articulation and the femoral distal articulation.   
     
     
         13 . The method of  claim 9 , the method steps further comprising:
 locating the first rotational component nearer to an intramedullary stem of the femoral prosthesis.   
     
     
         14 . The method of  claim 9 , the method steps further comprising:
 locating the first rotational component nearer to the distal articulation of the femoral prosthesis.